AD9432-105 Analog Devices, AD9432-105 Datasheet - Page 13

• Manufacturer Part Number: AD9432-105
• Description: 12-Bit, 105 MSPS Analog-to-digital Converter
• Manufacturer: Analog Devices

DATA OUTPUTS
The ADC digital outputs are latched on the board by two 574s;
the latch outputs are available at the 37-pin connector at Pins
25–36. A latch output clock (data ready) is available at Pin 21,
with the complement at Pin 2. There are series termination
resistors on the data and clock outputs. These can be changed if
required to accommodate different loading situations. Figure
16 shows a data bit switching and output clock (DR) at the
connector.
REFERENCE
The AD9432 has an on-chip reference of 2.5 V available at
VREFOUT (Pin 46). Most applications will simply tie this
output to the VREFIN input (Pin 45). This is accomplished
jumping E4 to E6 on the board. An external voltage reference
can drive the VREFIN pin if desired by strapping E4 to E3 and
placing an AD780 voltage reference on the board (not supplied).
TEK
2
STOP:
CH1
5.00GS/s
1.00V
CH2
1.00V
265 ACQS
[T]
T
M 5.00ns CH1
1.20V
C1 MAX
3.06V
C1 MIN
–390mV
C1 FREQ
105.4562MHz
DAC
The evaluation board has an on-board reconstruction DAC
(AD9752). This is placed only to facilitate testing and debug of
the board. It should not be used to measure the performance of
the ADC, as it will not accurately indicate the ADC performance.
The DAC output is available at SMB P1. It will drive a 50
load. Provision to power down the DAC is at Pin 15 at the DAC.
PCB LAYOUT
The PCB is designed on a four-layer (1 oz. Cu) board. Compo-
nents and routing are on the top layer with a ground flood for
additional isolation. Test and ground points were judiciously
placed to facilitate high-speed probing. A common ground plane
exists on the second layer. The third layer has three split power
planes, two for the ADC and one for support logic. The DAC,
components, and routing are located on the bottom layer.
TROUBLESHOOTING
If the board does not seem to be working correctly, try the
following:
The AD9432 Evaluation Board is provided as a design example
for customers of Analog Devices, Inc. ADI makes no warranties,
express, statutory, or implied, regarding merchantability or fitness
for a particular purpose.
Verify power at IC pins.
Check that all jumpers are in the correct position for the
desired mode of operation.
Verify VREF is at 2.5 V.
Try running encode clock and analog inputs at low speeds
(10 MSPS/1 MHz) and monitor 574 outputs, DAC output,
and ADC outputs for toggling.
AD9432